<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>click</title>
	<script type="text/javascript" src="js/jquery-1.12.4.min.js"></script>
	<script type="text/javascript">
		$(function () {
			$("#btn").click(function(){
				// click 时件
				$(".box").toggleClass("sty");
			})
		})


	</script>
	<style type="text/css">
		.box{
			width: 200px;
			height: 200px;
			background-color: gold;
		}

		.sty{
			background-color: green;
		}

	</style>
</head>
<body>
	<input type="button" name="" value="切换" id="btn">
	<div class="box"> </div>
</body>
</html>